Rate of erosion and exhumation of crystalline rocks in the Hunza Karakoram defined by apatite fission track analysis
Abstract
Rapid exhumation of rock massifs in the Hunza Karakoram has been caused by collision orogeny as well as intensive and variable climate-morphogenetic processes during the late Cenozoic. Apatite fission-track dating of crystalline rocks gave AFT-ages between 3.9 +/- 0.2 Ma to 9.9 +/- 0.4 Ma and constrained the period of a rapid exhumation and unroofing as Upper Miocene to Quaternary.
Time-temperature curves of the samples show two trends of exhumation rate: the Upper Miocene to Pliocene period of a slow rate of ca. 0.1 km/Ma followed by the Quaternary period of a relative rapid rate of ca. 2.6 km/Ma. The erosion rate reached up to a maximum of ca. 4000 m from the Upper Miocene to the present.
The high intensity of recent denudation and transport of weathered and eroded material suggest their long-term influence on the exhumation of deeper parts of the rock massifs during active orogenetic processes in the Hunza Karakoram.